We propose a plan to develop instrumentation and adaptive estimation techniques for implementing quantitative ultrasound methods to study renal physiology and disease mechanisms. Our first aim is to assemble an electronic system for estimating acoustic properties and forming parametric images at high speeds. The goal is to provide the means for investigating dynamic physiological processes and eventually to study human subjects. Our second aim is to investigate the sensitivity of these measurements and explore a potential solution to the important clinical problem of managing organ transplant rejection. Our third aim is to use Bayesian estimation methods to include the information acquired over the past three years on normal tissues into the estimation process and hereby improve measurement sensitivity. Our fourth aim is to construct test media and a CD phantom or use throughout the project but particularly in Aim 1; to measure important statistical properties of the data for use in Aim 3; to analyze measurement uncertainty and better understand the limitations of this approach to quantitative ultrasound. Having established feasibility of the techniques in the previous project period we now turn on developing and refining our hardware and software tools for investigating live tissues.